posted 09-28-2012 09:23 PM ET (US)            

---

If top end is your goal then the 14-1/4" x 17" Stiletto Advantage 4.75 or Turbo 1 4.75 is what you want.

You should raise the motor from the factory position by one set of bolt holes.

posted 09-29-2012 07:35 AM ET (US)            

---

tom,
14-1/4" x 18" Mercury Enertia or a 14-1/4" x 17" Stiletto Advantage 4.25 or Turbo 1.

is the stiletto 4.25 and turbo 1 the same prop?
how about enertia?

posted 09-29-2012 08:19 AM ET (US)            

---

quote:

---

tom the boat is on bottom holes move it up from there?

---

What does that mean?

posted 09-29-2012 08:20 AM ET (US)            

---

quote:

---

some have mentioned 14 19 pitch props?

---

14" is to little pitch. 19" is too much pitch. Don't listen to "some", whoever he is.

posted 10-01-2012 09:59 AM ET (US)            

---

What year is your Dauntless? What year is your motor? And what prop do you have?

I had a 2002 Dauntless 180 with Mercury OptiMax 135 for about 10 years. I moved the motor up to the "three holes up" position. My motor was equipped with a Mercury MiragePlus prop, 17-inch pitch, and that mounting height I experienced some prop ventilation in choppy seas and when making hard turns. Reports of the performance I experienced with the motor mounted at several different heights can be found here: http://continuouswave.com/ubb/Forum4/HTML/006379.html

posted 10-06-2012 06:44 PM ET (US)            

---

The recommended mounting height for a Dauntless 180 with an Optimax 135hp and 17" MIRAGEplus prop is 2 holes up from lowest location. There are several posts in the archives about this boat / motor combination. I have an '03 Dauntless 180 and raised the motor up this Spring with good results.

Tom

posted 10-07-2012 04:10 PM ET (US)            

---

obxharry,

30mph at 5000 rpm is too slow. I have the same boat/motor/ prop combo and reached about 41 mph at 5300 rpm with the motor at its lowest position. Look for issues with your prop or bottom condition.

posted 10-09-2012 09:10 AM ET (US)            

---

Is the boat trailered or does it sit in the water? If in the water, there could be marine growth on the bottom. Another possibility is the hub slipping. There are many more knowledgeable people than me on this site as to the cause, but since I have the same setup, I can say that for that rpm, you should be moving considerably faster.

Tom

posted 10-10-2012 11:09 AM ET (US)            

---

Then you have a 15-1/2" x 17" Mercury MIRAGEplus propeller and there is no way you are only running 30 MPH at 5000 RPM with that prop in a Mercury OptiMax 135 with its 2:1 gear ratio.

You are measuring speed wrong, your tachometer is wrong, or both.

posted 10-10-2012 08:32 PM ET (US)            

---

How is the condition of the boat's bottom? Covered with grass or barnacles? Bottom paint?

What is the condition of the current propeller? Does it have any dings, nicks, or bent blades?

What were the conditions when you previously measured the speed? Freshwater or saltwater? How many people on the boat? How much (in weight) gear on the boat? How much fuel in the tank? Was it a windy day? Was the water calm, choppy, or very rough? Did you have your bimini top up?

Does the boat have trim tabs? How about a Doel-Fin or some other hydrofoil?

Are you sure that you measured your speed in MPH rather than in knots?

posted 10-11-2012 10:26 AM ET (US)            

---

You are measuring speed with a GPS set to MPH and not knots?

You've made test runs in two opposite directions and averaged the results?

For an OptiMax 135 to travel 30 MPH at 5000 RPM with a 17" Mercury MIRAGEplus means there is over 25 percent calculated propeller slip. The MIRAGEplus will typically yield about 8 to 10-percent slip in a single motor application. Something is very wrong.